There’s always the crimes associated with black metal and its fans. Stuff like taking responsibility for inspiring arson of historic Christian churches in Norway and one musician being convicted of doing it himself, a few murders committed by musicians, a suicide by shotgun that inspired the guy’s bandmates to run and buy a camera to take a picture (which became an album cover for a future bootleg of their work) and then steal some of his skull fragments to make into necklaces (the band claims that the tale of cannibalizing some of his brain is just a rumor), that kind of thing. I guess the violence has dwindled these days.
You just answered your own question with your last paragraph. It’s a little of both. Getting into the business of explaining music scenes to those not in them is always really, really tricky.
What do The Decemberists and Destroyer (side project of Daniel Bejar of The New Pornographers) have in common? The nasal singing voice, for one, and the quirky lyrics - the word “carabinieri” (Italian police) is used in Watercolors Into The Ocean. In Your Blood, he sings, “I went for you/in military time/and then I waited well into the 2300s,” in a voice that emulates Bob Dylan. Not something that Britney Spears or even Audioslave or Incubus would do. Those bands are not classified as indie because there’s nothing that’s deliberatly self-conscious or quirky about their lyrics. Audioslave and Incubus are cool - very cool - but Daniel Bejar of Destroyer is hip. There’s a difference - again, it’s damn hard to explain. The interaction between Destroyer and its listener is like a 25 year old English grad school student trying to pick up a chick at a party. The interaction between Incubus and its listener is like a 21 year old rocker guy trying to pick up a chick at a party.
What do Built to Spill and The Decemberists have in common? Musically, very little. Lyrically, there’s a connection. When Doug Martsch sings “that brontosaurus must have been a thousand miles high” in Big Dipper, he’s joining Daniel Bejar and Colin Meloy of The Decemberists in the quirky-lyrics club. What does Built to Spill have in common with My Bloody Valentine? Lyrically, nothing, but musically, they share an emphasis on wall-of-sound guitar distortion. MBV uses enough of it to put off the average listener, who is not accustomed to such distortion. My Morning Jacket does the same thing with reverb - their songs are soaked in reverb to the point where the singer’s voice floats away like a ghost. This is not something that will get heavy radio play because most people don’t want to appreciate their music, they want to hear it. But an indie rocker will be more willing to listen to MMJ because he will be - typically - more open to music that deviates from the norm, and he will find MMJ’s songs hauntingly beautiful, and not meandering and boring as an average listener would. Even though MMJ is not usually thought of as an indie band, it enjoys popularity among the indie set because it’s so different.
What sets The Blow apart from Fergie of the Black Eyed Peas? The bumpin’ electronic beats are often similar - but the lead singer of The Blow sings, “when you’re holding me, we make a pair of parentheses” and “if something in the deli aisle makes you cry, of course I’ll put my arm around you and I’ll walk you outside.” She’s trying to be quirky with the lyrics instead of treating them as just something to accompany the music.
OK, so all these bands are listened to by a certain type of person. Young, in the 18-25 demographic, often a college student. Frequently former theater and band-geek kids, though not always. Usually artistically inclined - most indie kids I know are also into drawing, painting, or playing music themselves. They dress a certain way - blazers, glasses (it’s not uncool to wear glasses in the indie scene,) interesting shoes, usually vintage clothes often from goodwill or from used-clothing stores that specifically cater to the indie rock crowd (the ones here are cheap, not cynically overpriced.) I’m engaging in a little stereotyping here, sure, but the last big indie rock show I went to, pretty much everyone was dressed in a quirky way. Not necessarily all the same - there was a lot of variation - but they were definitely trying to capture the look. So those are indie kids. I can’t really explain it any further - you’d have to go to a show and look around.
This is my conception of indie as a scene, anyway. And this is from my firsthand experience in the indie community itself.
Actually, just read Wikipedia’s entry for indie rock. I think that sums it up perfectly.